Because the Jrk considers an input value of 2.1 V on SCL or SDA to be high, you can connect those pins directly to 3.3 V microcontrollers without needing a level shifter. If your microcontroller’s I²C interface is not 5V tolerant, it will usually still have a diode going from each I/O pin to its logic supply. These diodes clamp the voltage on the pins, preventing the Jrk’s pull-up resistors from pulling the pins too high. If you want to be extra safe and not rely on the clamping diodes, you can disable the Jrk’s pull-up resistors by going to the “Advanced” tab and checking “Disable I²C pull-ups”.
Hello, i want to use the Motor driver on an ESP32 over I2C (3.3V). So i want protect the ESP with clamping diodes, but i not sure how i have to use it, and what kind of diodes? Schottky diode? !
Many chips contain a two diode circuit like that built into their input pins to help prevent over voltage (generally from things like ESD). From a quick look, I did not see any mention of the ESP32 having those protections, so adding it yourself with Schottky diodes (or other signal diodes) makes sense. In that circuit the diode from 3.3V to the I/O pins will protect them from voltages higher than 3.3V and the diode from ground to the I/O pins will protect them from voltages lower than 0V. Since you are only planning to supply a 0-5V signal, you could use just the top diode. To limit the current through that diode, you should also add a small resistor (on the order of 100 ohms) between the output of the Jrk and input of the ESP32.
Some other options would be to add a 3.3V Zener diode between ground and each I/O pin along with the same series current limiting resistor between the Jrk and ESP32 or a simple voltage divider.
Hello Claire,
thanks for the fast answer and good explanation, the 100Ohm resistor make sense… and i now use your idea with the 3.3V Zener diode, thanks.
But one little question, i use the driver on 12V “Car Akku” with ~2m, 4mm^2 wires. I use a smooth acceleration for a Lineardrive with 9A Max. I can make space for 2x 470µF/35V Elkos (power capacitor) on my PCB, so make this sense? I think it is not necessary, but nice to have.
You didn’t say which Jrk G2 you have, so it is hard to evaluate how much load 9A is for the controller, but in general it shouldn’t hurt to add extra capacitance, so if you can make space, I would.
